Extrusion manufacturing is a known process for producing continuous structures. During extrusion manufacturing, a liquid matrix (e.g., a thermoset resin or a heated thermoplastic) is pushed through a die having a desired cross-sectional shape and size. The material, upon exiting the die, cures and hardens into a final form. In some applications, UV light and/or ultrasonic vibrations are used to speed the cure of the liquid matrix as it exits the die. The structures produced by the extrusion manufacturing process may have any continuous length, with a straight or curved profile, a consistent cross-sectional shape, and smooth surface finishes. Although extrusion manufacturing can be an efficient way to continuously manufacture structures, the resulting structures may lack the strength required for some applications.
Pultrusion manufacturing is a known process for producing high-strength structures. During pultrusion manufacturing, individual fiber strands, braids of strands, and/or woven fabrics are coated with or otherwise impregnated with a liquid matrix (e.g., a thermoset resin or a heated thermoplastic) and pulled through a stationary die where the liquid matrix cures and hardens into a final form. As with extrusion manufacturing, UV light and/or ultrasonic vibrations are used in some pultrusion applications to speed the cure of the liquid matrix as it exits the die. The structures produced by the pultrusion manufacturing process have many of the same attributes of extruded structures, as well as increased strength due to the integrated fibers. Although pultrusion manufacturing can be used to continuously manufacture high-strength structures, the resulting structures may lack the form (shape, size, precision, and/or surface texture) required for some applications. In addition, conventional pultrusion manufacturing may lack precise control over curing and the ability to dynamically change materials in the composite material during manufacture. Further, the variety of patterns and shapes integrated within the pultruded structures may be limited, thereby limiting available characteristics of the resulting structures.
Continuous fiber 3D printing (a.k.a., CF3D™) has recently been developed to address the shortcomings of extrusion and pultrusion manufacturing. CF3D involves the use of continuous fibers embedded within a matrix discharging from a moveable print head. The matrix can be a traditional thermoplastic, a powdered metal, a liquid resin (e.g., a UV curable and/or two-part resin), or a combination of any of these and other known matrixes. Upon exiting the print head, a head-mounted cure enhancer (e.g., a UV light, an ultrasonic emitter, a heat source, a catalyst supply, etc.) is activated to initiate and/or complete curing of the matrix. This curing occurs almost immediately, allowing for unsupported structures to be fabricated in free space. When fibers, particularly continuous fibers, are embedded within the structure, a strength of the structure may be multiplied beyond the matrix-dependent strength. An example of this technology is disclosed in U.S. Pat. No. 9,511,543, which issued to TYLER on Dec. 6, 2016 (“the '543 patent”).
Although CF3D™ provides for increased strength, compared to manufacturing processes that do not utilize continuous fiber reinforcement, improvements can be made to the structure and/or operation of existing systems. The disclosed additive manufacturing system and print head are uniquely configured to provide these improvements and/or to address other issues of the prior art.
The disclosed system is directed to addressing one or more of the problems set forth above and/or other problems of the prior art.